The present invention generally relates to a method and a system for providing control signals for operation of a plurality of machines in a manufacturing facility.
Many industrial products require multiple sequential processing steps during manufacturing. The quantity of manufactured industrial products in a production facility can be maximized by any one of many different production management systems depending on the nature of the products, the variety of the products, and the complexity of the processes employed during individual manufacturing steps, and the distribution and uniformity of processing time for each manufacturing step.
A production management system commonly employed to manufacture products that require a large number of processing steps is called a work-in-progress (WIP) management system. Metrics for measuring effectiveness of a WIP management system include average cycle time and average throughput. A cycle time is the time interval between beginning of the first processing step and the end of the last processing step for a product. The cycle time for any product divided by the raw processing time, i.e., the total time that the product actually spends during processing steps, is typically referred to as an X-factor. In other words, the X-factor for a given product is the ratio of the cycle time for a product to the raw processing time, which is the theoretical lower limit to the cycle time. Thus, the X-factor is a number equal to or greater than 1.0. A throughput is the amount of products that a manufacturing facility produces in a given time interval.
Optimal operation of a manufacturing facility can be effected by reducing the cycle times and increasing the throughput. However, there exists an efficiency frontier for these two goals of reducing the cycle time and increasing the throughput beyond which they become contradictory. Thus, at this frontier reducing the cycle time typically results in a reduction of the throughput, and increasing the throughput typically results in an increase in the cycle time.
However, a manufacturing facility's location vis-à-vis this efficiency curve is heavily dependent on the operations management system. Effective WIP management requires achieving the two goals simultaneously, or achieving at least one of the two goals without causing a substantial disadvantage with respect to the other goal.